Mischa Leinkauf and Mattias Wermke said Tuesday that the Brooklyn Bridge stunt was their latest work, and was intended as a celebration of public art and not as any political statement. On Wednesday, a law enforcement source told ABC News that the New York Police Department is starting to believe the artists’ description of the intricate flag.

The Berlin-based duo said that the flags that they put on top of the bridge were not bleached white but were made of white material and then hand-stitched so that it was done in Old Glory style with white stars and stripes. They said that they followed U.S. Flag Code in their handling of the American flags that they took down and promised to return them, but did not say where they are currently being stored or when they plan to give them back.

They also hope to see their white creations returned, telling the Associated Press ”we certainly would love to have them back.”

“White American Flags,” 2014 by German based artists, Matthias Wermke and Mischa Leinkauf.

Matthias Wermke and Mischa Leinkauf hoisted two hand-sewn white American flags on the towers of Brooklyn Bridge on the night of July 21, 2014 for their “White American Flags” art project.

“Ball is in their court,” the law enforcement source said. “They are realizing we are onto them and now they’re making overtures” to at least return the flags.

New York City Mayor Bill de Blasio said today that the police are still looking over their video surveillance tapes and they will have the final decision whether or not to prosecute.

“I am going to leave it to the NYPD to answer in specific. If they have violated the law, of course they should be prosecuted,” de Blasio said.

The artists have a history of daring performance art that has shown them scaling buildings and bridges across the globe and if the Brooklyn Bridge stunt is true, it’s not their first “performance” on the Brooklyn Bridge. The duo has pictures on their website showing balloons that they “installed” on the cables of the bridge in 2007.

In a statement, the artists said that their inspiration to change the flags was in tribute to the bridge’s creator, John August Roebling.

“He was a pioneer in the field of suspension bridges and his creations have become landmarks and unique architectural pieces of American history,” they wrote in the statement.

Wermke and Leinkauf installed flags sewn from high visibility construction vests on well-known buildings in Heilbronn and Vienna.

In “Entscheidungen,” Wermke hangs at a great height from urban architecture throughout Berlin, Germany.

They claim they used the anniversary of his death – July 21, 1926 after an on-site accident – as the justification for their timing this year and paid tribute to Roebling’s own inspiration before the stunt by visiting a church in Germany, the design of which reportedly influenced his creation of the Brooklyn Bridge.

“Before coming to the U.S. the artists attended a church service at Divi Blasii [church] with the two white American flags in their possession. It is not clear whether Roebling intended to include flagpoles: at any rate, the display of flags has been subject to some controversy and flagpoles have not always been a feature of the towers.”

The artists told ABC News that they would not be able to immediately respond due to the large number of media requests at this time, though they did share photos of a selection of their prior works.

Wermke walks at great heights through urban landscape from 2012-2014 in “Drifter.”

Their website includes slideshows of their work, which shows that the pair regularly scales buildings and landmarks in the name of art, including not only a number of landmarks in their hometown of Berlin but also smokestacks in Prague and a skyscraper in Tokyo.

Height is not the only fear factor in their work. One of the performers rode a makeshift handcar next to active train lines in Berlin while the other filmed the stunt in 2008. The next year, they built a hut on a concrete breakwater in Istanbuland lived there for three days.

“There are no safety nets in life,” Wermke said in an interview with German television channel DW that was released just eight days before they allegedly swapped out the flags. “Our work is like feedback to real life. Sometimes we don’t know what will happen. There may appear to be an element of safety where there is none.”